Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 3: Correlated Electrons: Heavy Fermions
TT 3.14: Vortrag
Montag, 26. März 2012, 13:00–13:15, H 3005
Ring Exchange Periodic Anderson Model for Bilayer 3He — •Jan Werner and Fakher Assaad — Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Würzburg, Deutschland
A unique feature of experiments on bilayer 3He[1] is that the second layer starts growing before the first solidifies. The fermions in the first layer close to solidification are thus slow, whereas the fermions in the second layer are light. This combination of slow and light fermions which can hybridize with each other is the basic ingredient of the Anderson model, and the experiment has been interpreted in terms of heavy fermion physics. However in contrast to the Anderson model, magnetism in the 3He first layer is dominated by three body ring exchange. We present a simple model, which captures all above features, including an independent scale for the ring exchange and the strict constraint of no double occupancy in the first layer. We solve this model using CDMFT with a hybridization expansion CT-QMC algorithm as impurity solver. Our results show remarkable similarities with the experiments: a suppression of the coherence temperature upon approaching the solidification point of the first layer accompanied by the onset of ferromagnetic correlations within the first layer.
M. Neumann, J. Nyeki, B. Cowan, und J. Saunders, Science 317, 1356 (2007)